Abstract: A container designed for the containment and storage of a plurality of tennis balls defining a package for retail sale thereof specifically structured to be convertible, after removal of the tennis balls, into a vessel for the storage and drinking of a liquid in a thermally insulated storage space. A cylindrical housing having the appearance of a conventional tennis ball package container surrounds and is spaced from an internal sleeve defining a storage space on the interior thereof wherein a closure assembly is provided to initally hermetically seal a plurality of tennis balls within the storage space and after removal, the closure assembly is further structured to provide fluid communication with liquids maintained within the storage space for drinking thereof.